Design Of Steel Structures — Part 1 MCQs with Explanations

In the design of steel bridges, the term "through type" refers to a bridge where the floor is supported at or near the bottom, but the top chords of the bridge are not braced. In other words, the traffic or load-carrying portion of the bridge passes through the structure formed by the trusses or girders without any obstruction or bracing at the top. This configuration provides an unobstructed path for traffic, allowing vehicles to pass through the bridge without any interference from structural members above. Through-type bridges are commonly used for spanning longer distances, such as over rivers or valleys, where a clear span is desirable to accommodate navigation or other considerations. Options A, C, and D are incorrect because: Option A: "Deck type" bridges have their traffic-carrying surface (deck) placed on top of, and typically supported by, the main girders or trusses of the bridge. Option C: "Half through type" bridges have characteristics that are intermediate between through-type and deck-type bridges, with the floor supported at or near the bottom and partial bracing at the top. Option D: "Double deck type" bridges have two levels of traffic-carrying surfaces, one above the other, with each level typically supported by its own set of girders or trusses. Therefore, the correct type of bridge described in the question is Option B: Through type.

Bolt Hole Diameter: In the design of steel structures, the diameter of a bolt hole is an important parameter to ensure proper fitting and to allow for slight misalignments during construction. Standard Practice: According to standard practice and codes, the diameter of a bolt hole is usually taken as the nominal diameter of the bolt plus an additional allowance to account for tolerances and ease of installation. Nominal Diameter +1.5 mm: The most common allowance added to the nominal diameter is 1.5 mm. This ensures that the bolt can fit through the hole without being too tight, while also maintaining structural integrity. Other Options: Gross diameter of bolt is not a standard term used for determining bolt hole diameter. Nominal diameter +2.0 mm is not as commonly used as the 1.5 mm allowance. Nominal diameter of bolt without any additional allowance does not account for tolerances and is not practical for construction. Therefore, the diameter of a bolt hole is usually taken as Nominal diameter +1.5 mm .

The external wind pressure acting on a roof is influenced by several factors related to the geometry and characteristics of the roof surface. One important factor is the slope of the roof . The angle or pitch of the roof changes the way wind flows over the surface, which affects the magnitude and direction of the pressure acting on it. Another factor is the degree of permeability of the roof . If the roof allows air to pass through openings or gaps, the airflow pattern and pressure distribution around the roof surface can change. Therefore, the external wind pressure depends on both the slope of the roof and the permeability characteristics of the roof. Hence, the correct answer is Option C: Both (A) and (B) .

Let's break down this question about designing steel structures in a simple way. First, what are racking forces ? Imagine you have a simple rectangular frame, like a picture frame or a doorframe. If you push hard on one of its top corners, the frame will try to get squashed and turn into a slanted shape, like a diamond or parallelogram. This sideways pushing force that tries to distort the shape is what we call a racking force . In real buildings, these forces usually come from things like strong wind pushing on a wall or an earthquake shaking the structure sideways. Now let's look at which parts of a steel structure's design consider these forces: i) Lateral braces Think of "braces" as diagonal bars or members that are specifically added to a rectangular frame. These diagonal pieces turn the squares or rectangles into stable triangles. Triangles are very strong and cannot easily be pushed sideways and distorted (racked). So, lateral braces are specifically designed to resist these racking forces . Their main job is to provide stability against horizontal forces and prevent the entire structure from collapsing or distorting sideways. ii) Chord members Chord members are the main horizontal (and sometimes vertical) parts of a frame or truss, like the top and bottom beams. While lateral braces *primarily prevent* the racking, the entire structure is a connected system. When racking forces act on a building, even if braces are present, the forces are still distributed throughout the entire frame. This means the chord members will also experience additional forces (like extra pushing, pulling, or bending) because of the racking effect on the overall structure. For example, the ends of the chords might experience more stress where they connect to columns. Therefore, when engineers design these main chord members, they must also consider these additional forces caused by racking to make sure the chords are strong enough and don't fail under all possible load conditions. In summary: - Lateral braces are directly designed to resist racking forces and maintain the frame's shape. - Chord members are also affected by racking forces , and their design must account for the stresses that racking induces in them as part of the overall structural response. Since both elements are important and their design must consider the effects of racking forces, the correct answer is Option C: Both (i) and (ii) .

Horizontal shear only is the correct answer to “Rivets connecting flange angles to cover plates in a plate girder are subjected to”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

Only shear stresses is the correct answer to “When the axis of load lies in the plane of rivet group, then the rivets are subjected to”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

Bottom chord area is the correct answer to “Hudson’s formula gives the dead weight of a truss bridge as a function of”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

5 is the correct answer to “The number of seismic zones in which the country has been divided are”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

10t is the correct answer to “Maximum pitch of rivets, used in steel stacks, is limited to (where t is thickness of thinner plate being connected)”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

Shear failure of the plate is the correct answer to “By providing sufficient edge distance, which of the following failures of riveted joint can be avoided”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

1680 mm is the correct answer to “The maximum permissible span of asbestos cement sheets is”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

Permitted at start and end of lacing system only is the correct answer to “The use of tie plates in laced columns is”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

Four times the weld size is the correct answer to “The effective length of a fillet weld should not be less than”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

30° is the correct answer to “Normally, the angle of roof truss with asbestos sheets should not be less than”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

1000 mm is the correct answer to “Pitch of tacking rivets, when double angles connected back to back and acting as tension members should not be more than”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

60% is the correct answer to “Efficiency of a riveted joint, having the minimum pitch as per IS : 800, is”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

Constant moment for all curvatures is the correct answer to “The moment-curvature relation at a plastic hinge is”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

Shear and bending forces is the correct answer to “The forces acting on the web splice of a plate girder are”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

More is the correct answer to “The actual thickness of butt weld as compared to the thickness of plate is usually”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

It is difficult to connect beams to the round sections is the correct answer to “A circular column section is generally not used in actual practice because”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

2 is the correct answer to “To minimize the total cost of a roof truss, the ratio of the cost of truss to the cost of purlins shall be”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

125 t2/h is the correct answer to “The connection of intermediate vertical stiffeners to the web, not subjected to external loads, shall be designed for a minimum shear force (kN/m) of (where, t = the web thickness in mm h = the outstand of stiffener in mm)”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

160 mm is the correct answer to “If the thickness of thinnest outside plate is 10 mm, then the maximum pitch of rivets in tension will be taken as”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

1.5 mm is the correct answer to “The difference between gross diameter and nominal diameter for the rivets up to 25 mm diameter is”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

Zero is the correct answer to “The slenderness ratio of a column supported throughout its length by a masonry wall is”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

Between 0.5 and 1.0 is the correct answer to “If the loaded length of span in meters of a railway steel bridge carrying a single track is 6 m, then impact factor is taken as”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

3.0 d is the correct answer to “Minimum pitch provided in riveted steel tanks is (where d is diameter of rivets)”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

105.5 MPa on net area is the correct answer to “The allowable tensile stress in structural mild steel plates for steel tank is assumed as”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

More than the load factor in determinate structures is the correct answer to “Other conditions being same, the load factor in indeterminate structures is”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

Rectangular beams up to 300 mm depth is the correct answer to “In case of timber structures, the simple bending formula M = fz may be applied for”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

6 zones is the correct answer to “As per IS : 875, for the purposes of specifying basic wind velocity, the country has been divided into”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

Transfer load from top of end posts to bearings is the correct answer to “The portal bracing in a truss bridge is used to”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

Is always greater than 1 is the correct answer to “The ratio of plastic section modulus to elastic section modulus”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

Increasing the length of the bearing plates is the correct answer to “The web crippling due to excessive bearing stress can be avoided by”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

Both (i) and (ii) is the correct answer to “Battening is preferable when the i) column carries axial load only ii) space between the two main components is not very large iii) column is eccentrically loaded The correct answer is”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

Both (i) and (iii) is the correct answer to “Bearing stiffeners are provided at i) the supports ii) the mid span iii) the point of application of concentrated loads The correct answer is”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

Both (i) and (ii) is the correct answer to “Study the following statements. i) Top lateral bracing prevents the sidesway buckling of the chord. ii) Sway bracing keeps the rectangular shape of the bridge cross-section. iii) Sway bracing transfers the load from top of end posts to bearings. The correct answer is”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

1.18 is the correct answer to “In case of timber structures, the form factor for solid circular cross-section is taken as”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

1.1 L is the correct answer to “The effective length of a battened strut effectively held in position at both ends but not restrained in direction is taken as”. This question is standard in competitive examination syllabi for Design Of Steel Structures.

More than d is the correct answer to “The diameter of base of conical flare of a steel stack is (where d is the diameter of the cylindrical part)”. This question is standard in competitive examination syllabi for Design Of Steel Structures.